As data rates and operating frequencies of wired and wireless communications increase, advanced technologies must be used to keep up with the rising clock rates for wired communications and the rising carrier frequencies for wireless communications. Devices using advanced technologies generally possess a very high ft, which is the frequency corresponding to an intrinsic transistor current gain of unity. In order to operate at high operating frequencies, these devices must have high transconductance and low input capacitance.
Complementary metal oxide semiconductor (CMOS) technology is typically used to implement these devices due to its relatively low cost and high level of integration. However, advanced CMOS devices typically have limited input capacitance. Therefore, circuits operating in these frequency ranges are very sensitive to parasitics, which are typically introduced by electrostatic discharge (ESD) protection circuits, bondwires and packages.
Bondwires provide connections between pins on the package and pads on the IC. Bondwires typically have a diameter of about 1.0˜1.2 mils and an inductance of approximately 1 nH/mm. Typical bondwire lengths for a packaged pin are about 3 to 4 mm. These bondwires have an inductance of about 3–4 nH. At 2.4 GHz, bondwires present about 45–60 ohms of impedance in series with the input or output impedance, which may alter the input/output impedance characteristics of the IC. IC designs must account for this impedance.
Some integrated circuits may need to reject signal energy at a first frequency to meet design parameters. For example, receiver circuits typically include mixers that mix input signals at f1 with a reference frequency f2. The mixer outputs signals at f1–f2 and f2–f3, where f3 is an image frequency. For example, the frequency f1 can be approximately 2.4 GHz and the frequency f2 can be approximately 2.1 GHz. The image frequency f3 is approximately 1.8 GHz and the mixer output signal frequency is at approximately 300 MHz.
An external filter is typically used to remove the mixing output that occurs due to the image frequency to improve signal quality. As can be appreciated, other types of ICs may also need to reject signal energy at other frequencies. These circuits may require external filters or other external components to reject the signal energy at the frequencies. These external filters and other components increase the cost of these circuits.
Impedance matching networks are often used to maximize signal energy that is coupled from an IC to a load. The impedance matching network typically includes an inductor and a capacitor. The inductor and capacitor are typically implemented off-chip. As can be appreciated, reducing or eliminating the off-chip circuit elements would help to reduce the cost of the impedance matching network. Other circuits may include external resonant circuits, which include off-chip inductors and/or capacitors. As can be appreciated, the off-chip circuit elements increase the cost of these circuits.